Final answer:
Rotor syndrome and Dubin-Johnson syndrome are differentiated by the presence of black liver in Dubin-Johnson syndrome, differences in coproporphyrin excretion patterns, and the histological appearance of liver cells. Rotor syndrome usually has milder symptoms and does not cause black liver pigmentation.
Step-by-step explanation:
The difference between Rotor syndrome and Dubin-Johnson syndrome can be distinguished by certain clinical, biochemical, and histological features.
Clinical Features
Both syndromes are characterized by congenital jaundice due to impaired hepatic excretion of bilirubin. However, symptoms of Rotor syndrome tend to be milder, and it does not cause the black liver associated with Dubin-Johnson syndrome.
Biochemical Tests
In both conditions, there is an increase in serum conjugated bilirubin. The differentiating factor lies in the hepatic excretion of coproporphyrin. In Rotor syndrome, total urinary coproporphyrin is normal but the pattern of coproporphyrin isomer excretion is abnormal. In contrast, Dubin-Johnson syndrome presents with a chronic increase in urinary coproporphyrin excretion and normal excretion pattern.
Liver Histology
The most striking distinction is seen in liver histology. Dubin-Johnson syndrome is characterized by a distinctive black or dark brown pigmentation of liver cells on biopsy, which is not present in Rotor syndrome.